Generally, the iris authentication device identifies a person by illuminating the eye of a person to be authenticated with a near infrared ray, by taking the eye image and the circumference image (as will be briefly called the “eye image”) with a camera, by extracting the iris information from the eye image obtained, and by comparing the iris information with the iris information which has already been registered in the iris information database. In this personal authentication, the satisfactory eye image has to be taken highly precisely for extracting the iris information of the person to be authenticated precisely. In case the person to be authenticated wears eyeglasses, however, the light reflected by the eyeglasses (as will be briefly called the “eyeglass reflection”) may overlap the iris portion, and the iris information may be unable to be extracted.
Thus, there has been proposed either a technique (e.g., JP-A-10-5195), in which an eye image having no eyeglass reflection is taken by disposing a plurality of illuminators having various incidence angles in advance and by using only the illuminator causing no eyeglass reflection selectively, or a technique (e.g., JP-T-2002-501265), in which one image having no eyeglass reflection is obtained by synthesizing a plurality of images having the eyeglass reflection at different positions.
For these techniques, however, it is necessary to dispose the plural illuminators at places apart from the camera such that the optical axes of those illuminators have various angles with respect to the optical axis of the camera. When those techniques are applied to a mobile terminal device such as a mobile telephone desired to reduce the size and weight, there arises a problem that the illuminators cannot be disposed at places apart from the camera. Another problem is that the number of trials is increased to form the plural images.